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authorJan Harkes <jaharkes@cs.cmu.edu>2017-09-27 15:52:12 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-24 08:33:42 +0100
commitfae5947129eb9f3cf0bc05bb4c770e5c2b2c8dd6 (patch)
tree96f0f4ffbacdf68d789de44111b90444569a5d1f
parent9980b8278338d4ba2064c32baa5db30f15a3ff96 (diff)
coda: fix 'kernel memory exposure attempt' in fsync
commit d337b66a4c52c7b04eec661d86c2ef6e168965a2 upstream. When an application called fsync on a file in Coda a small request with just the file identifier was allocated, but the declared length was set to the size of union of all possible upcall requests. This bug has been around for a very long time and is now caught by the extra checking in usercopy that was introduced in Linux-4.8. The exposure happens when the Coda cache manager process reads the fsync upcall request at which point it is killed. As a result there is nobody servicing any further upcalls, trapping any processes that try to access the mounted Coda filesystem. Signed-off-by: Jan Harkes <jaharkes@cs.cmu.edu> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/coda/upcall.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/coda/upcall.c b/fs/coda/upcall.c
index f6c6c8adbc01..7289f0a7670b 100644
--- a/fs/coda/upcall.c
+++ b/fs/coda/upcall.c
@@ -446,8 +446,7 @@ int venus_fsync(struct super_block *sb, struct CodaFid *fid)
UPARG(CODA_FSYNC);
inp->coda_fsync.VFid = *fid;
- error = coda_upcall(coda_vcp(sb), sizeof(union inputArgs),
- &outsize, inp);
+ error = coda_upcall(coda_vcp(sb), insize, &outsize, inp);
CODA_FREE(inp, insize);
return error;